Blade guide for motor-driven circular handsaws



June 5, 1945. c CHADDQCK 2,377,673

BLADE GUIDE-FOR MOTOR DRIVEN CIRCULAR HAND sfiws Filed Aug. 21, 1944 2 Sheets-Sheet 1 O /7 I V V TOR.

' June 5, 1945. c, (:HADDOCK 2,377,673

BLADE GUIDE FOR MOTOR DRIVEN CIRCULAR HAND SAWS Filed Aug. 21, 1944 2 Sheets-Sheet 2 Patented June 5, 1945 OFFICE BLADE GUIDE FOR MOTOR-DRIVEN CIRCULARS'HANDSAWS Clarence-F. Chaddock, Los Angeles, are. Application August 21, wig-sentinel). 550,432

' p '3 Claims. (Cl.143.-43)' This-invention relates to an attachment in the way of a blade guide for a portable, motor-driven hand-saw equipped with acircular cutting blade and mounted upon a flat base plate formed with air-elongated slot through which the blade protrudes to thework, the saw blade and motor driving-the same being pivotally supported in mounting elementsin such manner that the blade may be tilted laterally to or from the perpendicular for theypurpose of sawing at anydesired angle or bevel, within a limited range, such saw being of the conventional skilsaw type.

The primary object of the inventionis to provide an attachment for mounting transversely at the rear of the base plate of a saw of the kind referred to,the said attachment having a guide finger pivotally mounted on the outer side thereof adapted for positioning for following through along the saw cut as formed by the forwardly movingisaw blade, asmeans for guiding the blade straightly ahead and in a straight line as the tool travels forwardly over the work.

Another object of the invention is to provide for a portable hand saw of thekind referred to, the same including and being mounted upon a fiat and v elongated and longitudinally slotted base plate through which the circular blade proe jects to the work, and the said base plate having an upturned rear flange-an elongated attachment bar formed at its ends with clips adapted to frictionally engage the ends of the said upturned rear flange of the base plate and formed along its upper edge to accommodate and clear the structural features and elements of the tool, and a guide finger adjustably pivoted at its upper end to the upper margin of the attachment bar, the lower end of the finger extending below the lower edge of the attachment bar andformed and adapted to follow along through the saw cut, as means for maintaining the saw blade in a straight away course through the work, and whether the saw blade is set for perpendicular cutting or for angular or bevel cutting. Withthe stated, objects in view, togetherwith such other objects and advantages as may appear from the specification, attention is directed to the drawings as showing a preferred embodiment of the invention and wherein:

:1T'igure 1 is a rear end elevation of 'aportable, motor driven, circular hand saw as located upon a piece of work in theprocess of sawing the same, and having myimproved blade guideattachmentwmounted on the rear end thereof, the adjustable {guide finger of the attachment being positioned as for following through perpendicularly along :the saw cut as formed by the tool, and thus directing the saw straightly ahead, the angular adjustability of the guide finger being indicated in dotted lines, as required for bevel enlarged scale of the blade guidefinger as posi-i Figure 2lis a side elevation of the rear end portionof the assembly "as indicated in Figure 1; Figure 3 is albottom plan'view of the assembly indicatedin F'ig. 1. l

Figure 4 is an outer side view of theublade guide attachment asremoved from the saw or tool. Figure 5 is an innerside view of the blade guide attachment (as removed from the saw ortool. t Figure 6 is .a perspective view on an enlarged scale of the oblong base plate comprising one element are conventional circular hand-saw, and upon the rear upturned margin of which in invention is mounted.

Figure 7 is a detail in perspective and on an tioned withinasaw-cut formed in the work. t Figure 8 is a side elevationon the scale of Figure? of the blade guide finger as remove from itsattachment bar. i

This invention is designed for mounting upon,

any conventional form ofcportable, motor driven;

circular hand-saw, such as here represented generally at 5, and sometimes referred to'as a Such a saw comprises a flat, oblong base plate 6, rectangular inform, and having its margins turned up angularly all around, as indicated at 1 and 8. The rear upturned margin 8 is of substantial height as, shown, and is cut langularly across its upper edge at the left end of the ele-' ment as indicated at 9. Through the apex of this angular margin is formed a shaft receiving bore In, the same being in a line cutting per- 1 pendicularly thesaid plates and passing through the elongated saw-slot II at the rear end of the said slot, this slot being conventionally formed along through the left side of the base plate in parallelism with the lateralmargin thereof.

A bracket I2 is mounted to the forward end of the base plate 6 in longitudinal alignmentwith the saw-slot ll, thisbracket being *also formed with a shaft receiving bore '13 disposed in. exact longitudinal alignment with the bore 4010f the upturned rear margin-8. t

The saw unit as such comprises the usual casing l4 elongated in form and pivotally mounted at itsends between the forward bracket I12 and upturned rear margin-8 of the base plate, by I means of the elements l5 extended from the ends of the casing andsecured by means of short bolts 16 passed through the said elements and through the bores 10 and I3, all in usual manner. Thecasing I4 is provided with a handle I! rearwardly extended, and a motor driven circular saw I8 is keyed on the outer end of a drive 0 shaft 49 and disposed at the left side ofthecasing M, the said saw blade being-protruded down through the slot ll of the base plate to the desired extent for engaging the work. The shaft open corners on the base plate.

' I9 is extended transversely into the casing and in place at the rear end of the base plate. 'In.

this mounting the bights of the said clips pass down between the upturned ends of the rear margin 8 and the lateral margins I forming thereat The left end of the bar 20 is of substantially greater width than the right end, as indicated at 20a and 20b, and the wider end 20a is pierced through by a pivot pin hole 200 and by an arcuate and horizontally extended slot 20d, both located in a plane passed vertically therethrough and medially through the slot ll of the base plate 6. The otherwise elongated and relatively narrow right end 2012 of the bar 20 may be further cut away and reduced immediately at its juncture with the widened left end 20a, to provide a bolt head clearance 20c, adapted to clear the outer end of the rear bolt l6 when the device is mounted in place.

A blade guide finger 22 is formed of a short length of flat and narrow strip material, preferably of metal, the end portions thereof being twisted and turned ninety degrees relative to one another, as indicated at 2211. The upper end 221) of this finger is disposed flatly at the outer side of the widened left end 2011 of the bar 20, in an outwardly spaced relation to the bore or hole 200, and the finger is then pivotally secured to this end of the bar 20 by means of a short stud or pin 23 which is passed through the hole 200 and through the upper end of the finger 22. This upper end of the finger is prevented from buckling inward to the bar by means of a small, expansive coil spring 24, which is seated over the stud and braced at its ends between the bar and the upper end of the finger. The lower end 220 of thisfinger thus extends vertically down the end 20a in a perpendicular relation thereto, and across the arcuate slot 2011, the lower extremity of the finger being extended somewhat below the lower edge of the bar 20, as indicated at 22d, in the drawings. A stop pin 25 is soldered transversely upon the finger 22 in alignment with the slot 20d, the inner end of this pin being projected freely through the said slot. Thus the lower extremity 22d of the finger may be moved back and forth along the arcuate slot 28d, and is adapted to serve as a thin guide point or tip for following along through the saw cut 26, as the same is formed in and along the work piece 21 by the circular saw blade l8 working through the slot ll of the base plate 6, as the toolis pushed for- Wardly over the work. Thus the cutting may be directed straightly and regularly through the work. Because of the outward press of the spring 24 the free lower end of the finger is maintained in proper contact and alignment with the bar 20, and thi spring also serves to frictionally hold the finger to any position of adjustment to which it may be set, either perpendicularly to the base plate 6, or angularly to either side of the perpendicular, as may be required for bevelcutting the work.

. In the use of this attachment, the saw blade is merely set to the desired cutting angle in the customary manner, and the saw is started into the work in the desired direction and angle. When the saw blade penetrates into the work sufficiently to clear the margin thereof, the lower guide tip of the guide finger is moved and set into the mouth of the saw-cut, where it is held friotionally as stated. Thereafter the saw is moved forwardly and the guide tip of the guide finger follows along through the cut and directs the saw blade straightly through the Work.

While I have here shown and described a certain embodiment of the invention and have shown specific structural features thereof, the embodiment shown as well as the specificfeatures thereof, may be changed as desired, within the scope of the claims.

Iclaim:

1. In a device of the kind described, for attachment at the rear end of the base plateof a conventional portable, motor-driven hand-saw equipped with a circular saw blade, a flat and elongated attachment bar provided with clips at its end for frictionally engaging the upturned rear margin of the base plate of the saw for transversely mounting the bar thereto, the said bar being formed at its upper margin to conformto the configurations and structural features of the tool on which it is mounted, a guide finger pivoted at its upper end to the upper margin of the attachment bar in operative alignment with the saw blade, the lower extremity of this finger being depended below the lower edge of the attachment bar and formed as a-pointed guide tip adapted to follow along through the saw cut as formed by the travel of the blade through the work.

2. In a device according to claim 1, there being an arcuate slot formed through the attachment bar in vertical alignment below the point of pivotal connection of the finger with the said bar, and a stop pin anchored transversely to the finger in alignment with the said arcuate slot, the inner end of the said pin being extended through the slot as means for limiting the movement of the guide finger along the slot.

3. In a device of the kind described, a flat and elongated attachment bar formed with clips at its ends for frictionally engaging the ends of the upturned rear flange of the base plate of a conventional portable, motor driven hand-saw of the skilsaw type, a guide finger pivoted at its upper end to the upper margin of the attachment bar rearwardly of and in operative alignment with the saw blade, the lower extremity of this finger being depended below the lower edge of they attachment bar and formed as a pointed guide tip adapted to follow along through the saw cut as formed by the travel of the saw through the work, there being an arcuate slot formed through the attachment bar in vertical alignment below the point of pivotal connection of the guide finger with the bar, a stop pin secured transversely to the guide finger with the inner end of the pin extended through the said arcuate slot as means for limiting the lateral movement of the finger, and means for holding the guide finger toany adjusted position relative to said arcuate slot.

CLARENCE F. CHADDOCK." j 

